Distribution of valve-gear systems for rotary machines

ABSTRACT

The invention concerns a distribution system for a rotary machine of the type having a rotor with an epicycloidal profile comprising N lobes and disposed eccentrically inside a stator having N + 1 lobes, each lobe of the stator forming with the rotor a working chamber having a variable volume. The distributor disc is driven in a circular movement of translation by a combination of two eccentric movements, one of which is that of the rotor and the other is an eccentric movement having its centre displaced with respect to the axis of the machine and is rotated by the rotational movement of its shaft at the same angular speed. The invention is applicable to rotating compressors, motors and other rotating machines.

United States Patent [191 Brille [451 Dec. 17, 1974 [5 1 DISTRIBUTION OF VALVE-GEAR SYSTEMS 3,671,] 54 6/1972 Kolbe et al 418/61 B FOR ROTARY MACHINES [75] Inventor: Maurice G. Brille, Billancourt, Primary Examiner l,ohn Vrabhk France Attorney, Agent, or FtrmStevens, Davls, Miller &

Mosher [73] Assignee: Regie Nationale Des Usines Renault,

lllancourt, France ABSTRACT [22] Filed: Feb. 1, 1973 Appl. No.: 328,599

[30] Foreign Application Priority Data Feb. 8, 1972 France 72.04093 [52] US. Cl 418/61 B [51] Int. Cl. F0lc 1/02, F040 1/02, F040 17/02 [58] Field of Search 418/61 B [56] References Cited UNITED STATES PATENTS 2,966,860 l/l96l Maynard 418/178 3,106,163 10/1963 Mosbacher.... 3,224,421 12/1965 Peras 3,364,907 1/1968 .leanson 418/61 B 3,658,450 4/1972 Woodling 418/61 B The invention concerns a distribution system for a rotary machine of the type having a rotor with an epicycloidal profilecomprising N lobes and disposed eccentrically inside a stator having N l lobes, each lobe of the stator forming with the rotor a working chamber having a variable volume.

The distributor disc is driven in a circular movement of translation by a combination of two eccentric The invention is applicable to rotating compressors,

motors and other rotating machines.

10 Claims, 3 Drawing Figures PATEHTEL SEC! 719% SHEET 1 2 DISTRIBUTION OF VALVE-GEAR SYSTEMS FOR ROTARY MACHINES tages and their usual use in piston compressors, these clapper valves have numerous drawbacks, especially for their use in rotary machines; to which the Applicant is giving his more particular attention.

In fact, these rotary machines comprise quite naturally by their construction, contrary to piston machines, a number N l of working chambers which is fairly large, which gives them greater uniformity of working, but which necessitates a larger number of clapper valves. These clapper valves, generally arranged in a ring and which must be capable ofbeing dismantled for inspection or replacement, have with their manifolds a relative bulk which is excessive and which substantially reduces the advantage of 'small overall size of these rotary machines. in addition, these clapper-valves considerably restrict the surface area of the casing which can be used for cooling highly desirable for the compressor.

It should also be observed that these rotary machines can rotate more rapidly than piston machines, that the working chambers operate at higher frequencies, andthat the free clapper-valves are liable to work badly at these high frequencies.

Finally, the reversibility of these machines tocompressed gas motors does not permit the use of clappervalves and necessitates a positive distribution system synchronized with the speed of the driving shaft.

For all these reasons, it is advantageous to utilize both as a compressor and as a motor, a rotating distribution system which covers and uncovers at appropriate moments the communication ports between the working chambers and the intake and'outlet manifolds for the fluid. Systems of this kind exist currently in hydraulic pumps and hydraulic motors.

Unfortunately, these distributors applied to compressors and motors for compressed gas do not possess adequate lubrication and cooling in order to accept the high pressures and speeds which are furthermore per- I mitted by the whole of the device.

The friction of the discs on their slide faces would involve large losses of power and rapid losses of fluidtightness and wear.

The object of the present invention is a distributor which fulfills the same purpose as that described above, which to that end remains synchronized with the shaft, but in which the movement is a circular translation of low linear speed, utilizing the particular kinematics of the rotary machine in question.

ln machines of this kind, the drive of the rotor is obtained from a gear having KN teeth where-K is a whole number, fixed on this rotor and engaging with a fixed crown-wheel having K (N l) teeth, rigidly fixed to the stator.

- and of its crown-wheel According to the invention, the distribution is effected by a distributor disc held against a friction face, mounted freely for rotation on an eccentric crank-pin of the central rotatingshaft of the machine and comprising a toothed crown-wheel fixed onthe said distributor, centered on the axis of the said eccentric crankpin and identical with the fixed crown-wheel of the stator, and driven by a pinion identical with the driving pinion of the rotor, also centered on the said rotor and rigidly fixed thereto, the i said distributor being displaced by the action of rotation of the central shaft at the same angular .speedfor all the points of its surface in a single circular movement of translation.

More precisely, on the rotor is fixed agear of KN teeth (N being the number of lobes of the rotor and K being a whole number), engaging with a crown-wheel A fixed on the stator, of K (N l teeth. The rotoris eccentric with respect to the central axis by a value:

E=MK(N+'l)KN/2=MK/2 in which M is the module of the gears.

In one advantageous form of embodiment of the in vention, the gear of- KN teeth on the rotor is brought into engagement with a second crown-wheel of the same diameter as the first, having K (N l) teeth. If -the centre of. this second crown-wheel is held on the axis of the machine, it will remain stationary like the first, but if the centre of this second crown-wheel is displaced with respect to this axis, with the condition of maintenance of engagement, it will rotate with the shaft at the angular speed at and all the points of the crownwheel will describe the same small circles at the angular speed (0, and at a linear speed which becomes lower as the displacement of the centre becomes less.

The movement of the second crown-wheel will be a circular translation.

The distributor is the holding plate of this second crown-wheel. lt is itself maintained on its centre by an eccentric mounted on the main shaft and'having as'its eccentricity the above-mentioned displacement, it will have the same movement of circular translation as the crown-wheel. Thisdistributor has N-l- 1 pairs of orifices, one for the intake of the gas and the other for its outlet, each pair being located in front of the outlet opening of the channel which communicates with each working chamber.

A second characteristic feature of the invention is the sliding swivel mounting of the working part of the distributor plate on the crown-wheel holding plate in According to a third characteristic feature of the invention, the admission and exhaust manifolds are arranged in a circular manner in order that the-distributor may be automatically applied against its slide-fac'e by a chosen value of pressure of the gas compressed by the machine or of the driving gas. This construction could be compared with the operation of a slide-valve of a steam engine, which valve has an alternating rectilinear movement which could be considered as a projection I of the circular movement of the present distributor, this movement permitting a single member to ensure the distribution for the N 1 working chambers of the machine.

A fourth characteristic feature of the invention is the coating of the slide-face with a non-metallic material having a very low coefficient of friction, for example a combination of Teflon and graphite. This eliminates the necessity of lubrication for the distributor. It should be noted that the use of such materials is permissible, since the temperature of the gases is always lower than 200C. 7

An example of construction of the distribution device forming the object of the invention will be described below with reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic representation in exploded perspective view of the kinematics of the operation of the distributor;

FIG. 2 shows a view in longitudinal section of the whole of a compressor comprising a rotor with three lobes, namely N 3, following a preferred example of embodiment of the invention;

FIG. 3 shows a front view in the direction of the arrow F of FIG. '2, of the corresponding distributor wheel, showing the profile of the distributionorifices.

In FlG. 1 there is shown the general axis (1 -a of the machine, which is at the same timethe axis of the driving shaft (compressor) or driven shaft (motor) and the axis of the stator. There has been chosen in this case by way of example, a machine in which N 3, that is to say the stator having the centre a has four lobes C and the rotor having its centre at O has three lobes d with an eccentricity E. v

On the axis 00 of the rotor is keyed the pinion f having a pitch-circle radius equal to SE. This pinion engages with the crown-wheel g having a pitch-circle radius of 4E fitted on the stator. It is known that the rotation ofthe shaft a -,-a at the speed to causes rotation of According to the invention, the axis 00 is extended to O and the pinion f is extended up to f,, the pitch circle of the pinion f, having thus the same radius 3E as the pitch circle ofthe pinion f and the same setting; it

is a parallel section-of the same pinion.

There is engaged with La second crown-hweel 3 having the same pitchcircle radius g, that is to say.4E without first defining the position of its centre 1. Its eccentricity OJ, is equal to E, like 0 a, and 0 namely:

In the plane perpendicular to the axis a -,-a 0 1, may be orientated through 360 around 0 the angled: 0 a, may be chosen at any value comprised between 0 and 360. Also, in the isosceles triangle 1,0 0. there will be the relation:

p I a, 2Esin 01/2 the same radius p with the same speed in. The plane j has a circular movement of translation.

In the case wherea 0, then p O, the circle g is fixed as is also the circle g and its extension. The plane j is stationary if a then 11' 2E and the amplitude of the circular translation is a maximum, as is also its linear speed.

a may be chosen in such manner that the linear speed of the plane is a minimum, while retaining however sufficient amplitude of movement to ensure correctly the action of distribution which is referred to below.

Since N 3 and there are four working chambers, the plane j will be divided into four equal sectors, each of which will possess two orifices k and m communicating respectively and continuously with the inlet and outlet of the fluid at the front of the plane and successively covering and uncovering the orifice q of the conduit n of the working chamber corresponding to the sector of the plane considered.

. It will be observed that there 'could be two separate conduits n and n, the orifices q and q of which would be respectively controlled by the orifices k and m of the distributor plane. The amplitude could then be smaller,

as could also the speed and the friction, but at the cost of an increase in dead space.

In FIG. 2, the compressor is constituted by its stator 1 which carries the profile having the reference C on FIG. 1, by its rotor 2 which carries the profile reference d in FIG. 1, and by the side plates 3 and 4.

The central shaft 5 having its axis a -a is mounted on roller bearings 6 and 7 housed in the side-plate 3 and the casing 22. it carries the eccentric crank-pin 40 having its axis'at 0 -0 about which pivots the rotor 2 by its sleeve bearing 10. At its two extremities, the shaft 5 carries counterweights to balance the eccentric mass of the rotor. One ofthese weights is carried by the driving pulley 8 while the other has the reference 9.

' The pinion 11 (referenced at fin FIG. 1) having a radius 3E is mounted fixed on the rotor '2 on the bearing 10. The pinion 1 l engages on one side with the toothed crown-wheel 12 having a radius 4E (referenced g in FIG. 1) rigid with the side plate 4, andaccordingly fixed, and on the other sidewith the crown-wheel 13 having a radius 4E (referenced g in FIG. 1) fixed on the hub 14 of the distributor end-plate, which rotates on its sleeve-bearing 17 on the eccentric crank-pin 18 (having the axis'l 1 in FIG. 1).of the shaft 5.

The movement of the hub 14 is a circular translation movement; all the points of 14 describe circles having I a radius 1,, a

On the hub .14 is slidably keyed theexternal crownwheel 15 with a key 19 which also permits a slight swivel movement of this crown-wheel on the outer spherical face 20 of the hub 14. This outer crownwheel 15 constitutes the distributor proper. Its mount- [4, namely a circular translation.

outlet of the shaft 5 and the face in order to facilitate its cooling and holding in position by the effect of the clapper-valve.

Bolts 26 clamp together in a single block the stack of v parts 21, 3, 1, 4 and 22 ensuring an easy and rapid dismantling of the assembly and good accessibility to all the parts.

When working as a compressor, the pulley 8 drives in rotation the shaft 5, the eccentric and the gear of which 11-12 drive the rotor 2 in its conjoint bearing in the stator 1. The air or fluid to be compressedis successively drawn-in, compressed and evacuated from each chamber 27 of the stator through a single opening 28 formed in the side-plate 4 and the plate or friction slide-face 16.

FIG. 2 shows the chamber 27 at its maximum volume, the crown-wheel having just closed the-communication of the opening28 with an admission port 29 (FIG. 3) previously in the compression-delivery phase. The diametrically-opposite chamber, the lobe of which is completely filled by that of the piston, has just completed its delivery phase, and the delivery port 30 moves away and is replaced by the adjacent admission port 29. The other two chambers set perpendicularly and not being shown in FIG. 2, are set symmetrically,

one in the compression-delivery phase and the other in the admission-suction phase. The communication of the suction port 29 with the circular manifold 23 is effected through a circular channel 31 and grooves 32 formed in the interface of the crown-wheel l5 and the hub 14. The communication of the exhaust port 30 with the circular delivery manifold is effected by a circular peripheral groove 33 in the crown-wheel 15.

The opening and closure of the ports 29 and is I contact permits, in certain applications, the slide-face 16 to be made of synthetic material with good friction properties, such as Teflon, and also the various lateral joints 34 of the rotor and the circular joints 35 of the crown-wheel 15, making it possible to eliminate any lubrication of these zones and any contamination of the compressed fluid.

The circular translation movement, similar to a surface-finishing operation, tends to wipeout any accidental scratches in the slide-face 16 due to solid impurities, and thus to maintain good fluid-tightness.

Thisfluid-tightness is also ensured by the maintenance of the crown-wheel 15 under pressure against the slide-face 16, by a clapper-valve effect. When starting-up, the simple pressure on the crown-wheel 15 of the joint 35 opposite to the slide-face 16 is sufficient to ensureits forcible application, subsequently effected by the delivery pressure. The balancing of this pressure in order to reduce the friction losses can be regulated by the dimensioning of the pressure surface areas.

When a pressure regulator is employed, the positive clapper effect of the distribution by slide-valves and slide-face according to the invention does not permit automatic regulation in free air on no-load working, as

in clapper-valve compressors. In this case, it is provided to put the rear zones of the joints-straps or sealing straps (not shown) of the stator to, free air by a channel 36, which enables these joint-strap or sealing straps to be pushedto thebottoms of their housings and, during these periods, effects a sweeping of air cleaning away the impurities and dust which have accumulated in the chambers andthe zones of the joints.

In this case of operation as a compressor with a ceiling pressure, a non-return valve 42 is provided on the outlet circuit and a calibrated valve 40 is placed on the outlet 36 of the connection to free air of the rotorstator joints.

The shape of the delivery port 30 is chosen in such tor, this same orifice 30 is defined in such manner as to I ensure the chosen rate of expansion.

Finally, as has previously been stated, the single conduit 28 may be replaced by two conduits, one for the entry of fluid and the other for its outlet, and these con- I said rotor (K rotor by a first eccentric crank pin on which saidrotor is rotatable, v j 1 said rotor being driven in rotation by said'pinion, said pinion being concentric with an eccentric bearing and engaging said crown wheel, said stator having the same axis as therotatable shaft,

a distributor disc supported against a friction face of a side plate, said disc being rotatably mounted on a second eccentric crank pin on said rotatable shaft,

a toothed crown wheel rigidly fixed on said distributor disc and centered on the axis of said second pin,

and I said disc crown wheel being driven by said pinion. 2. The rotary machine of claim 1 in which said disc crown wheel has the same diameter and module as said stator crown wheel.

3. The rotary machine of claim 1 in which admission and evacuation ports communicate with at least one chamber of said stator through at least one opening in 'said side plate.

distributor casing on the side plate, said circuits being adapted to open into an orifice of said friction face.

5. The rotary machine as claimed in claim 4, in which said admission circuit is constituted by an annular manifold which-is closed on said distributor disc at the level of the hub to crown crown-wheel interface, said interface being provided with a plurality of grooves for communication with the opposite face of said disc.

6. The rotary machine as claimed in claim 4,. in which a calibrated valve is mounted on the outlet of a circuit connecting rear cavities of rotor-stator sealing straps to free air,and a non-return valve mounted on said evacuation circuit, to ensure the operation of said machine, working as a compressor on no-load and at the ceiling pressure.

7. The rotary machine as claimed in claim 4,. in which said evacuation circuit is constituted by a circular evac-.

pressure of said evacuation circuit.

8. The rotary machine as claimed in claim 7, in which the friction face is made of a synthetic'material having a base of Teflon and graphite.

9. The rotary machine as claimed in claim 7, in which a casing contains the evacuation manifold concentric with an annular admission manifold which is in turn.

concentric with a roller bearing of said central shaft, the separation of said manifolds being ensured by circular fluid-tight joints. I

10. The rotary machine as claimed in claim 9, in which the pressure of said joint separating said admission and evacuation manifolds is applied against said distributor crown-wheel so as to ensure a forced application of said crown-wheel against said friction face. 

1. A rotary machine comprising: a rotor with N lobes, a pinion with KN teeth rigidly fixed on said rotor (K being a whole number), a stator having N + 1 chambers, a crown wheel with K (N + 1) teeth fixed on said stator, a centrally disposed rotatable shaft coupled to said rotor by a first eccentric crank pin on which said rotor is rotatable, said rotor being driven in rotation by said pinion, said pinion being concentric with an eccentric bearing and engaging said crown wheel, said stator having the same axis as the rotatable shaft, a distributor disc supported against a friction face of a side plate, said disc being rotatably mounted on a second eccentric crank pin on said rotatable shaft, a toothed crown wheel rigidly fixed on said distributor disc and centered on the axis of said second pin, and said disc crown wheel being driven by said pinion.
 2. The rotary machine of claim 1 in which said disc crown wheel has the same diameter and module as said stator crown wheel.
 3. The rotary machine of claim 1 in which admission and evacuation ports communicate with at least one chamber of said stator through at least one opening in said side plate.
 4. The rotary machine as claimed in claim 1, in which said distributor disc is formed by a central hub and by a distribution crown-wheel swivel-mounted externally on said hub and rigidly fixed for rotation with said hub, and orifices of admission and evacuation circuits of a distributor casing on the side plate, said circuits being adapted to open into an orifice of said friction face.
 5. The rotary machine as claimed in claim 4, in which said admission circuit is constituted by an annular manifold which is closed on said distributor disc at the level of the hub to crown crown-wheel interface, said interface being provided with a plurality of grooves for communication with the opposite face of said disc.
 6. The rotary machine as claimed in claim 4, in which a calibrated valve is mounted on the outlet of a circuit connecting rear cavities of rotor-stator sealing straps to free air, and a non-return valve mounted on said evacuation circuit, to ensure the operation of said machine, working as a compressor on no-load and at the ceiling pressure.
 7. The rotary machine as claimed in claim 4, in which said evacuation circuit is constituted by a circular evacuation manifold closed on the periphery and the rear face of said external crown-wheel of said distributor disc so as to ensure its maintenance in position on said friction face by a clapper effect, under the action of the pressure of said evacuation circuit.
 8. The rotary machine as claimed in claim 7, in which the friction face is made of a synthetic material having a base of Teflon and graphite.
 9. The rotary machine as claimed in claim 7, in which a casing contains the evacuation manifold concentric with an annular admission manifold which is in turn concentric with a roller bearing of said central shaft, the separation of said manifolds being ensured by circular fluid-tight joints.
 10. The rotary machine as claimed in claim 9, in which the pressure of said joint separating said admission and evacuation manifolds is applied against said distributor crown-wheel so as to ensure a forced application of said crown-wheel against said friction face. 